7/04/08 DIS08 1

Selection of ZEUS results

• hadronic final states

• heavy flavors

• energy dependence of tot(*p)

• diffraction

• inclusive DIS measurement (H1/ZEUS F2 and PDFs)

• FL determination

Halina Abramowicz

7/04/08 DIS08 2

HERA Luminosity

Available luminosity HI HII (pb-1)HER EHER Epp=920 GeV e=920 GeV e++p 125 p 125 190 190 ee--p 19 210 MER Ep=575 GeV e+p 8LER ELER Epp=460 GeV e+p 14

HERA stopped operation on June 30, 2007HERA stopped operation on June 30, 2007

Polarised e e+, e-

(P0.30)

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Hadronic final states - Jets

QPM BGF - low x QCDC - large x

Usually source of information about S

In CC also sensitivity to quark flavors

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Inclusive jets in CC ep

NLO - MEPJET with ZEUS-S PDFs

PDF uncertainties included

e-

e+

e-/e+

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Hadronic final states -

€

KS0

€

KS0

All Q2 data mostly Q2<1 GeV2

• Fit M and of 4 resonances• Include interference for 2+

states (SU(3) symmetry)

• 2/ndf=86/97 Nf0(1710)=4058820 (5) candidate for glueball (0+) • fit without f0 2/ndf=162/97

Hunt for glueballs

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Hadonic final states -

€

KS0

€

KS0

• f0 also seen in TASSO/L3 - cannot be pure glue state• masses lower than PDG (includes other measurements)• widths agrees with PDG

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Heavy flavor production

• gluons• pQCD (various mass schemes)• not included in PDFs

Charm, beauty production with sensitivity to

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Heavy flavors production

b e+jet b

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Beauty production

Latest summary

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Exclusive beauty production

1998-2007 ZEUS data with Ep=920GeV1998-2007 ZEUS data with Ep=920GeVintegrated luminosity 410pb-1integrated luminosity 410pb-1

55 signal from signal from (1S), (1S), (2S), (2S), (3S)(3S)

10421 events

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Exclusive processes

)(,)(

|)|largeat||(,)()(,)()(

))(()(

)()(

2

)1(4||2

222

QRWRr

ttnWteQbdt

d

MQnQ

WW

kij

nIP

tb

n

IP

⇒

∝∝∝⇒

+∝⇒

∝⇒

−−−

−

δ

δ

soft

hard

soft

hard

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W dependence of tot(p)

Donnachie Landshoff

Cudell et al. (after rejecting some data)

What does it mean soft?

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W dependence of tot(p)

Detect scattered electronQ20, measure energy

Calibrate 6mT with BH

Minimal trigger in CAL Subtract overlays

e 27.5 GeV p

HER920 GeV

LER460 GeV

ZEUS preliminary

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Inclusive diffraction

• Large fraction of DIS events have LRG (visible 10%)

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

DGLAPDGLAP

LRG cannot be generated by DGLAP.LRG cannot be generated by DGLAP.Maybe it is there in the initial condition?Maybe it is there in the initial condition?

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LPS method

Large Rapidity Gap (LRG) method

Mx methodxL = pz

’/pz

Inclusive diffraction - selection

Selection methods

Difference in proton dissociation and statistics

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Inclusive diffraction - normalisation

Pythia tuned to FPC and LPS (xL<0.90)

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Inclusive diffraction - comparison

LRG(MN=Mp)=MX(MN<2.3 GeV)· 0.83

H1=LRG (MY<1.6 GeV) · 0.87

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Inclusive diffraction in DIS soft vs hard

Inclusive diffraction in DIS comes out to be a soft phenomenon, evenat large Q2

Cudell et al.

ZEUS(prel.)

• LPS/LRG Regge fit• W-dep. of D

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F2 and PDFs - HERA I H1/ZEUS combined

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F2 and PDFs - HERA I H1/ZEUS combined

Systematic uncertainty greatly reducedwhen data combined

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F2 and PDFs - HERA I H1/ZEUS combined

Note MSTW08 is as yet

unpublished - a prerelease

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F2 and PDFs - HERA I H1/ZEUS combined

xS

xuV

xdV

xg

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High Q2 - a taste of future

Electroweak couplings of light quarks (using e-

L,R)

Global QCD fit

ZEUS limit on quark Rq<0.62 10-16 cm

LEP limit on electron Re<0.28 10-16 cm

e-

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FL - measurement principle

High s - Ep=920 GeV Low s - Ep=460 GeVMedium s - Ep=575 GeV , not reported here

fixed x,Q2

•Sensitivity to FL requires high y •Challenge - high y means low electronenergy and large background from p•Need additional tools - use CTD/MVD hit information - use 6mT to normalise p

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FL - control plots

920 GeV 460 GeV

MC FL=0

N(p)<15%

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Reduced cross section as a function of x,Q2

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Reduced cross section as a function of x,Q2

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Reduced cross section as a function of x,Q2

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FL

7/04/08 DIS08 30

Those are exciting times

Many more results and many more details

will be presented in the parallel sessions

Summary